feat(admin): Phase 1 注册邀请码逻辑 — 码必填 + kind 分流 + validate-invite + 注册页码优先重做

后端:Invitation.kind(join_team/create_team)+ team 可空 + migration;RegisterSerializer 邀请码必填,
create_team 开新团队当 owner+发试用额度、join_team 幂等入伙不重复发额度,删「空码开团队」;
validate-invite 免登录验码端点;团管发码恒 join_team;InvitationSerializer 增 kind/team_name。
前端:注册页码优先(验过才展开;create_team 填团队名 / join_team 只读团队名,不暴露团队列表)、
邀请链接 ?invite= 自动验码、api.validateInvite、验码行/状态提示样式(仅 token)。
测试:accounts 22/22 单测过(RegisterInviteCodeTests + ValidateInviteTests);
无头 e2e _admin-p1.mjs 全断言过 + 0 console error;tsc+build 绿。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/qa/visual-parity/_admin-p0.mjs

@@ -5,7 +5,7 @@ import { chromium } from "playwright";
 import fs from "node:fs";
 import path from "node:path";
 
-const BASE = process.env.BASE || "http://localhost:5173";
+const BASE = process.env.BASE || "http://127.0.0.1:5188";
 const API = process.env.API || "http://127.0.0.1:8010";
 const OUT = path.resolve("output/admin");
 fs.mkdirSync(OUT, { recursive: true });